The architecture firm behind the ill-fated Diana memorial fountain has spoken out ahead of its reopening, blaming its early problems on its huge appeal to the public.

'We didn't fully anticipate how popular it would be,' said Neil Porter of Gustafson Porter, who co-designed the fountain. 'When it was inundated with people at the start they had a hard time standing up. Especially when the autumn came and the grass became sodden underfoot.'

The 10-month-old fountain, situated near the Serpentine in London's Hyde Park, is due to open on Friday after four months of work to replace the surrounding grass with a rubberised track. Made of resin and stone chippings, the new track cost £200,000 to install and is designed to stop visitors slipping over.

The result, after four months of renovations, is a very different set of surroundings for the fountain from the simple elegance that Gustafson Porter originally intended. The Royal Parks Agency has erected a fence around the fountain in a bid to manage the crowds expected to flock to the memorial when it reopens this week.

But Porter said he was pleased with the eventual result. 'We were involved in the design and the layout of the track. Tonally, it matches the grass. Hopefully, when the interest dies down a bit, the fence will be able to come down,' Porter said.

The fountain has been beset by problems since it opened last year. Leaves clogged its pump system forcing it to be closed for a week last July. Algae formed on the granite surface making it slippery underfoot.

But Porter said despite the negative publicity he was proud of the memorial. 'You can imagine there have been moments when we wondered whether it was the wisest thing to get involved with. But we're proud of it and what we have achieved.'